This invention relates to improvements in a wear plate that is specifically designed for convenient and removable installation in the pedestal opening of a railway truck side frame in order to prevent wear on the load bearing surface of the pedestal. The wear plates described herein represent improvements over those described in my U.S. Pat. Nos. 3,897,736 and 4,203,371.
As described in the aforesaid patents, the weight of a railway vehicle is supported upon wheel and axle assemblies wherein the axles carry roller bearing assemblies to minimize friction. An insert is provided between the outer bearing rack and the pedestal opening in the side frame, which is referred to as a bearing adaptor. The purpose of the adaptor is not only to complete the support structure, but also to equalize or distribute the load placed on the roller bearing.
The bearing adaptor has an upper surface that is in direct engagement with the downwardly facing surface in the pedestal opening. In service, limited movement or frictional sliding occurs between the bearing adaptor and the pedestal surface, which causes the frame surface to become worn. Excessive wear results in sloppiness between the axle and frame and weakening of the frame at a critical load bearing location. Repair of the frame surface is both expensive and time consuming, since the worn surface must be ground flat and renewed by welding a flat plate into the opening.
The clip-on wear plates described in the aforesaid U.S. Pat. Nos. 3,897,736 and 4,203,371 prevent wear on the frame surface if they are installed on a new frame or a reconditioned frame. A problem arises, however, when attempting to install such wear plates over a previously worn surface. If the surface is not flat or is uneven, the wear plate will not ride solidly in the opening and will be stressed unevenly, which may cause failure in highly stressed areas.
The upper surface of the bearing adaptor has a central recess therein extending parallel to the axle, whereby the load is borne on relatively raised surfaces or lands on either side of the recess to ensure proper force distribution to the bearing assembly. Wear is thus confined primarily to lands and the corresponding bearing surfaces on the frame. Under excessive wear conditions, the entire upper surface of the bearing adaptor may engage the frame, causing the bearings to become pinched and overheated.